Outbreaks Slow PRV Eradication

A number of outbreaks this past winter have certainly slowed progress in the pseudorabies (PRV) eradication program. But industry officials meeting just before World Pork Expo say they are still committed to finishing on time. Completion is set for the end of 2000.Areas of Indiana, Iowa and Minnesota were hardest hit by PRV outbreaks.According to federal USDA veterinarian Arnold Taft, a combination

A number of outbreaks this past winter have certainly slowed progress in the pseudorabies (PRV) eradication program. But industry officials meeting just before World Pork Expo say they are still committed to finishing on time. Completion is set for the end of 2000.

Areas of Indiana, Iowa and Minnesota were hardest hit by PRV outbreaks.

According to federal USDA veterinarian Arnold Taft, a combination of factors led to the breaks. To save money in a down market, some producers stopped vaccinating pigs, which led to more infection in finishing units. These operations became naive and broke with PRV after being exposed to actively infected herds, some of which have virtually refused to cooperate in or complete PRV cleanup, he says.

That's certainly been the case in Indiana, which got most of the negative press for registering 60 new cases of PRV so far in '98, says John A. Johnston, DVM, director, Swine Division, Indiana Board of Animal Health.

Already 33 herds have come off quarantine and "we feel like we are back on track," adds Johnston. In all, Indiana has 223 PRV-quarantined herds.

"The feeling is that the herds that have not been working to clean up are the ones we need to crack down on," adds Max Rodibaugh, DVM, Swine Health Services, Frankfort, IN.

One way Indiana hopes to start that ball rolling is by limiting its parity 3 easement on the test and removal program, says Johnston. The federal test and removal rule calls for sows in all quarantined, PRV-infected herds to be tested before or at the time of farrowing. Those sows testing positive must be removed for slaughter or placed in isolation for slaughter within 15 days of weaning. Boars must also be removed within 15 days of testing positive for PRV.

Indiana had modified the federal test and removal rule to include only parity 3 and above breeding animals. But Johnston says the board of animal health now believes that providing that exception produces a "never-ending cycle of potential infection." With that exception, young, naive females could be continually exposed to older, positive sows.

Indiana officials are proposing to revoke that exception for non-complying herd owners effective Jan. 1, 1999. Herds would then be viewed as non-compliant if they don't meet cleanup deadlines. Those deadlines require that all herds quarantined on or before Jan. 1, 1997, must be released from quarantine by Jan. 1, 1999.

"Producers are required to be on active cleanup plans, but if they are not ready for release from quarantine by Jan. 1, 1999, they will be considered non-compliant, which takes away the parity easement," he explains.

Test, Removal Concerns Faster cleanup and removal from quarantine are the goals of the test and removal program, says Taft.

That is doable, except where 70-90% of the herd is positive, says Indiana veterinarian Rodibaugh. "Then it becomes a huge hit on those animals at weaning, forcing that producer to turn over that herd so much faster when we are not in the best of times economically."

In Iowa, the test and removal law becomes effective Jan. 1, 1999. Bob Welander, a section veterinarian for the State of Iowa in southeast Iowa, says large producers were scared when they learned about the test and removal law because they realized that for the first time it made cleanup plans mandatory for all herds infected with PRV.

If producers dump large numbers of positive sows, it would destroy their isolation and acclimation programs and breeding schedules.

So Welander has started testing these large herds now. If positive for PRV, they are placed on whole herd vaccination programs. Sows are being tested and the positive ones removed over a phased period of time. "It's better to have the culling done in two to three hits instead of just one big one come Jan. 1," he explains.

"With this test and removal program, hopefully we can get everybody working on cleanup at the same time," adds Lawrence Birchmier, DVM, PRV program director, Iowa Department of Agriculture.

Terry Mangold, DVM, Washington, IA, agrees. "Getting all producers on the same page is the big problem. Unless we can maintain continuity from producer to producer and get all producers operating in a similar manner, we may have reached a threshold level on cleanup."

For every three herds we clean up, it seems like we find another infected herd, Birchmier says.

Still, Iowa has made "tremendous progress" in its state PRV eradication program, going from nearly 4,200 infected herds four years ago to about 720 infected herds today, says Welander.

Minnesota added 34 new PRV quarantined herds this spring, released 45, for a total of 154, says John Landman, DVM, PRV coordinator, state board of animal health.

It's been a trend going back 18 months, he says. Finishing floors will break with PRV, but on traceback testing, the nurseries and the sow herds supplying the pigs for finishing test negative.

Landman suspects the problem is a lapse in biosecurity. When hogs are marketed, protect against hogs and people tracking back and forth between the livestock truck and the finishing barn.